The early years of the combination antiretroviral therapy (ART) era have brought about dramatic reductions in the morbidity and mortality associated with HIV infection in industrialized countries. Yet, the critical importance of adherence in optimizing treatment outcomes quickly became evident. My prior work has shown that injection drug users (IDUs) underutilize ART, and are at high risk for inadequate adherence and poorer treatment outcomes when therapy is used. Tuberculosis treatment with directly observed therapy (DOT) has proven remarkably effective in addressing issues currently being confronted in HIV management - promoting adherence, achieving clinical success, and avoiding drug resistance. Methadone maintenance is an effective treatment for opiate addiction and provides a feasible setting in which directly administered antiretroviral therapy (DAART) may be provided to HIV-infected patients. I propose to conduct a prospective clinical study to determine the effectiveness of DAART provided in a methadone maintenance clinic. Clinical outcomes will be compared in DAART participants and matched participants in the Johns Hopkins HIV Cohort Study. My hypothesis is that DAART will be effective in a methadone treatment center and will be associated with improved HIV treatment outcomes compared to standard care. The specific aims of this project are to 1) assess 1-year retention in DAART and associated factors, 2) assess the temporal trend of adherence in DAART and its association with viral suppression, 3) compare virologic and immunologic responses to therapy in DAART participants and matched patients receiving standard care, and 4) compare the incidence of opportunistic diseases and death in DAART participants and matched patients receiving standard care. This proposal builds directly on my prior work and lays the foundation for a randomized, multi-site trial of the DAART strategy. My career development plan is based on the Graduate Training Program in Clinical Investigation, which includes comprehensive coursework at the Johns Hopkins School of Public Health, structured mentoring, and guidance from a thesis committee. My career plan and research proposal are consistent with my long-term goals of becoming an effective independent investigator, and optimizing treatment outcomes in HIV-infected IDUs.